i think in a normal game the card goes to the discard pile face up.
But on this online version you don't see the opponents discarded card , that is maybe normal?
If i play live with someone we always discard face up.

The card says, "choose one and discard the other." It doesn't say anything about burying or mixing the card into the deck. "Discard" would mean putting it on top of the discard file.

I think I questioned this at the beginning of the open beta, too, but never heard a response.

I just assumed they were doing it this way to simplify the mechanics of Counter-Attacking.

Yeah - good point.
But they could perhaps do a "pop-up" showing the opponent what had been discarded, so you need to pay attention at the moment, rather than have the card be constantly on display atop the discard pile.

In most games it doesn't matter much, but in those tense and exciting close matches that we all love (I hope) it could be an important factor ("OK, so my opponent discards an Assault left flank, guess things will happen elsewhere").

An added complication is that the discard shows the last card (the recon-1) that was played.

Would it be more confusing to show the discarded card on the pile? Would someone think that they could incorrectly counter-attack the discarded card.

Do you really keep a detailed track of what cards have been played? I tend to know how many counter-attacks have been played, if the airpower, general advance, DHq, Armour Assaut, TFH, BEL have been played. But I don't track every card. (Limited processing capacity.)

Being able to see the opponent's discard in"normal" Memoir can be interesting. At the same time, it can be interesting for your opponent not to see the discard. The other night, early in a game, I kept an Infantry Assault and tossed Ambush. It was nice being the only player who knew that Ambush was not a threat.

(By the way, I haven't noticed, after Ambush is played, whether it stays on top of the pile or goes away.)

@Phread: I find that paper can be useful for keeping track of cards played.

Being able to see the opponent's discard in"normal" Memoir can be interesting. At the same time, it can be interesting for your opponent not to see the discard. The other night, early in a game, I kept an Infantry Assault and tossed Ambush. It was nice being the only player who knew that Ambush was not a threat.

(By the way, I haven't noticed, after Ambush is played, whether it stays on top of the pile or goes away.)

@Phread: I find that paper can be useful for keeping track of cards played.

In F2F games we play that the discarding player can choose to discard face up or face down as he like. Adds to the metagaming psych war Memoir is.
Seeing a good card there makes the other player fear what was chosen. Not seeing it can be equally frightful.
I like Recon-1 a lot.